Answer:
25
Step-by-step explanation:
First find the length of the diagonal of a square of side 4 inches:
d^2 = 4^2 + 4^2 = 2*4^2 = 32. Then the diagonal of the cube has length
sqrt( 32 + 4^2) = sqrt(32+16) = sqrt(48) = 4sqrt(3).
Convention in algebra is that we use letters such as a, b, c, etc., for parameters and letters such as x, y z, and so on, for variables.
Thus the parameters here are a, b and k. k is the constant of proportionality.